Fast wicking for liquids is desirable in many commercial products such as diapers, personal hygiene, sanitary products etc. Fast wicking is typically achieved by converting paperboard products into defiberized fluff pulp that has a high surface area to enable fast wicking. Fluff pulp is then positioned within the product so that it can wick bodily fluids, for example, away from their point of deposition.
Fluff pulp is formed from paperboards made by conventional papermaking technologies. Once the paperboard sheet is manufactured, for example by a wet-laid process, it is defiberized mechanically, using a device like a hammermill. The defiberized fluff pulp can then be air-laid with particles of superabsorbent polymers or other super-absorbent materials. Such particles, capable of absorbing up to one hundred times their weight in water, are admixed with the defiberized fluff pulp to form the absorbent core for the product.
Formation of fluff pulp from paperboard typically uses mechanical means to break the strong intermolecular hydrogen bonds that form between neighboring cellulose fibers during the papermaking process. A significant amount of energy is required to overcome the strength of the intermolecular bonds and break a paperboard into individual fibers. Because the energy required for mechanical breakdown methods is expensive, alternate technologies have been employed to reduce the formation of hydrogen bonds during papermaking.
As an example, debonder compounds are used during papermaking for this purpose. Debonders bind to the fiber surface, preventing the formation of hydrogen bonds by acting as a spacer between neighboring cellulose molecules and fibers. A typical configuration for a debonder includes quaternary ammonium salts and a long hydrophobic chain. In such a debonder, the cationic ammonium group can attach the debonder molecule to the anionic fiber surface, while its hydrophobic chain acts as a spacer between cellulose fibers/molecules. With the debonder in place, fewer bonds form between the cellulose fibers. With fewer bonds holding the fibers together, less energy is required to break the fibers apart.
Although these debonders produce a paperboard that requires less mechanical energy for forming fluff pulp, the debonder and its hydrophobic moiety are retained within the paper product. Retention of the hydrophobic moiety in the final product can be undesirable. For example, the presence of the hydrophobic component decreases the wicking property of the resulting fluff pulp. Hence there is a need for an approach that reduces the hydrogen bonding among the cellulose fibers, so that they can be easily broken apart, but that does not affect the hydrophilic properties of the resulting fluff pulp. Desirably, an appropriate debonder would both decrease the energy of defiberization and maintain comparable or improved wicking speeds.